Syntheses, structures and properties of copper(II) and cobalt(II) metal–organic frameworks based on R-isophthalate (R = –CH3 or –C(CH3)3) and 1,1′-(1,4-butanediyl)bis(imidazole) ligands

Three new complexes [Cu2(mip)2(bbi)]n (1), {[Cu2(tbip)2(bbi)2(H2O)]·2H2O}n (2) and {[Co2(tbip)2(bbi)2]·2H2O}n (3), were prepared through hydrothermal reactions of Cu(II) and Co(II) acetate with H2mip or H2tbip (H2mip = 5-methyl isophthalic acid and H2tbip = 5-tert-butyl isophthalic acid) and the flexible ligand bbi (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)). All these complexes were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Complex 1 exhibits a 3D network, which are constructed from 2D carboxylate layer and bbi pillar. Complex 2 possesses a 2D layer structure, and exists extensive hydrogen-bonding interactions, while complex 3 is constructed from 2D layers which consists of alternating left- and right-handed helical chains, and further assembled to form a 3D framework by hydrogen-bonding interactions. The thermal stabilities of the corresponding complexes have been briefly investigated. In addition, dominant antiferromagnetic coupling was observed in complex 1.

Graphical abstractThree new coordination polymers with diverse structures were prepared through hydrothermal reactions of Cu(II) and Co(II) acetate with 5-methylisopthaliac acid or 5-tert-butyl isophthalic acid and the flexible ligand bbi (1,1′-(1,4-butanediyl)bis(imidazole)). The structural differences among these complexes highlight the effects of metal ions and ligands on framework formation of the complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide